Try writing the Veterans Administration. I had an idea that my dad was living in IL back in the 1980's so I wrote the Regional VA HQ out there and they advised me to:

1. Write him a letter, but do NOT seal the envelope.
2. Place the unsealed letter inside another envelope addressed to the VA.
3. VA would review the letter to make sure it was not threatening, etc.
4. VA would address the unsealed letter to the veteran.

After that it would be up to the veteran to respond to your letter.

Another method is to do the same with the DMV in the area you think he might be in. The DMV will match up the info and forward your letter to the driver on file with same SSN, name, etc. Again, it will be up to the driver of record to respond.

I was not able to obtain my dad's Navy records until AFTER his death.
Hope this helps.

Georgia Walker-Adams